ALSA: firewire-lib: code refactoring for cache position in tx packets

When sequence replay is enabled for media clock recovery, current
implementation caches sequence descriptors from packet descriptors in tx
packets. Helper function for the purpose do not necessarily have good
readability.

This commit refactors relevant functions by renaming structure members,
function name, and function local variables.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20230107023214.29132-4-o-takashi@sakamocchi.jpSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/amdtp-stream.c

@@ -495,7 +495,7 @@ static unsigned int compute_syt_offset(unsigned int syt, unsigned int cycle,
 static unsigned int calculate_cached_cycle_count(struct amdtp_stream *s, unsigned int head)
 {
 	const unsigned int cache_size = s->ctx_data.tx.cache.size;
-	unsigned int cycles = s->ctx_data.tx.cache.tail;
+	unsigned int cycles = s->ctx_data.tx.cache.pos;
 
 	if (cycles < head)
 		cycles += cache_size;
@@ -509,12 +509,12 @@ static void cache_seq(struct amdtp_stream *s, const struct pkt_desc *descs, unsi
 	const unsigned int transfer_delay = s->transfer_delay;
 	const unsigned int cache_size = s->ctx_data.tx.cache.size;
 	struct seq_desc *cache = s->ctx_data.tx.cache.descs;
-	unsigned int cache_tail = s->ctx_data.tx.cache.tail;
+	unsigned int cache_pos = s->ctx_data.tx.cache.pos;
 	bool aware_syt = !(s->flags & CIP_UNAWARE_SYT);
 	int i;
 
 	for (i = 0; i < desc_count; ++i) {
-		struct seq_desc *dst = cache + cache_tail;
+		struct seq_desc *dst = cache + cache_pos;
 		const struct pkt_desc *src = descs + i;
 
 		if (aware_syt && src->syt != CIP_SYT_NO_INFO)
@@ -523,10 +523,10 @@ static void cache_seq(struct amdtp_stream *s, const struct pkt_desc *descs, unsi
 			dst->syt_offset = CIP_SYT_NO_INFO;
 		dst->data_blocks = src->data_blocks;
 
-		cache_tail = (cache_tail + 1) % cache_size;
+		cache_pos = (cache_pos + 1) % cache_size;
 	}
 
-	s->ctx_data.tx.cache.tail = cache_tail;
+	s->ctx_data.tx.cache.pos = cache_pos;
 }
 
 static void pool_ideal_seq_descs(struct amdtp_stream *s, struct seq_desc *descs, unsigned int size,
@@ -881,11 +881,9 @@ static inline u32 compute_ohci_it_cycle(const __be32 ctx_header_tstamp,
 	return increment_ohci_cycle_count(cycle, queue_size);
 }
 
-static int generate_device_pkt_descs(struct amdtp_stream *s,
-				     struct pkt_desc *descs,
-				     const __be32 *ctx_header,
-				     unsigned int packets,
-				     unsigned int *desc_count)
+static int generate_tx_packet_descs(struct amdtp_stream *s, struct pkt_desc *descs,
+				    const __be32 *ctx_header, unsigned int packet_count,
+				    unsigned int *desc_count)
 {
 	unsigned int next_cycle = s->next_cycle;
 	unsigned int dbc = s->data_block_counter;
@@ -895,7 +893,7 @@ static int generate_device_pkt_descs(struct amdtp_stream *s,
 	int err;
 
 	*desc_count = 0;
-	for (i = 0; i < packets; ++i) {
+	for (i = 0; i < packet_count; ++i) {
 		struct pkt_desc *desc = descs + *desc_count;
 		unsigned int cycle;
 		bool lost;
@@ -1199,7 +1197,7 @@ static void process_tx_packets(struct fw_iso_context *context, u32 tstamp, size_
 {
 	struct amdtp_stream *s = private_data;
 	__be32 *ctx_header = header;
-	unsigned int packets;
+	unsigned int packet_count;
 	unsigned int desc_count;
 	int i;
 	int err;
@@ -1208,10 +1206,10 @@ static void process_tx_packets(struct fw_iso_context *context, u32 tstamp, size_
 		return;
 
 	// Calculate the number of packets in buffer and check XRUN.
-	packets = header_length / s->ctx_data.tx.ctx_header_size;
+	packet_count = header_length / s->ctx_data.tx.ctx_header_size;
 
 	desc_count = 0;
-	err = generate_device_pkt_descs(s, s->pkt_descs, ctx_header, packets, &desc_count);
+	err = generate_tx_packet_descs(s, s->pkt_descs, ctx_header, packet_count, &desc_count);
 	if (err < 0) {
 		if (err != -EAGAIN) {
 			cancel_stream(s);
@@ -1226,7 +1224,7 @@ static void process_tx_packets(struct fw_iso_context *context, u32 tstamp, size_
 			cache_seq(s, s->pkt_descs, desc_count);
 	}
 
-	for (i = 0; i < packets; ++i) {
+	for (i = 0; i < packet_count; ++i) {
 		struct fw_iso_packet params = {0};
 
 		if (queue_in_packet(s, &params) < 0) {
@@ -1611,7 +1609,7 @@ static int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed,
 			// possible to cache much unexpectedly.
 			s->ctx_data.tx.cache.size = max_t(unsigned int, s->syt_interval * 2,
 							  queue_size * 3 / 2);
-			s->ctx_data.tx.cache.tail = 0;
+			s->ctx_data.tx.cache.pos = 0;
 			s->ctx_data.tx.cache.descs = kcalloc(s->ctx_data.tx.cache.size,
 						sizeof(*s->ctx_data.tx.cache.descs), GFP_KERNEL);
 			if (!s->ctx_data.tx.cache.descs) {

sound/firewire/amdtp-stream.h

@@ -145,7 +145,7 @@ struct amdtp_stream {
 			struct {
 				struct seq_desc *descs;
 				unsigned int size;
-				unsigned int tail;
+				unsigned int pos;
 			} cache;
 		} tx;
 		struct {